Published at national confrence on emerging trends in communication ETC 09 on 20-21 feb 2k9 at swami vivekanad institue of engg and technology.
Astt Prof ECE Dept
LCET Katani Kalan
Low birth weight or sick newborns are at greater risk of developing hyperthermia than the normal weight babies. The aim of paper is to provide the protective environment for the small babies, which are at the greater risk of sudden death syndrome. As to minimize the stress of their thermoregulatory system, it is necessary to maintain the room temperature at some required level. Recurrent life threatening episode of apnea in infants involve complex problems of diagnosis and management. The need to evaluate high risk babies using medically sound principles prompted the development of a uniform set of guidelines, which should be used while making any pediatric equipment. The risk of heat loss is more than the heat production in new born babies because the surface area of baby is more than its mass, so more heat loss takes place by conduction. The method of keep baby warm will depend upon weight, age, health, availability of staff and equipment. Basically, two types of equipments can be used to give essential life support to the premature:1)Radiant heat warmers. 2) Incubators
1. Radiant Warmer Has Certain Advantages Over The Incubators:
1) Compact design.
2) Transport easiness
3) Open care system so oxygen consumption increases.
4) Easy access of baby.
5) Low cost than incubators.
6) Due to radiant heater more clinical care is provided.
7) Frequent interaction with doctors and nurses.
The major disadvantage of radiant heat warmers is that they have increase water loss. The amount of water loss totally depends upon the fluid requirements of the patient. In radiant warmers the approximate water loss is 22.6 ml/kg/day. This disadvantage can be overcome by proper heat shielding. The radiant warmers meets the thermoregulatory requirements of patient if designed according to most recent international standards and provide an adequate and secure environment. Immature thermoregulatory mechanism and small baby size means preterm.
2. Objective: Neonates are prone to temperature maintenance problem and thermal stress is associated with increase morbidity and mortality. So the radiant warmer should have ideal method of temperature recording and the recording should be done at fast rate. The design should be such that the equipment is easily operable and cost effective. Accuracy in temperature measurement and maintenance is the aim of this paper. In the commercially available radiant heat warmers to maintain the temperature at the required level, which can be selected, the PI (proportional integral) control is used. The solid-state control system is designed to provide accurate and reliable temperature control and an integrator help to reduce steady state error to zero. The system reduces temperature fluctuations and overshoots to a minimum and provides rapid response to adjustments in the set temperature.The proportional heater control is achieved by burst firing of the heater circuit. This results in the heater switching ON and OFF at varying rates according to the demand. When starting from cold the heater is on continuously, but as the selected temperature is approached the demand is reduced and heater start cycle on and off. If the selected temperature is lower than the measured temperature the heater remains off. This radiant warmer design have PID temperature controller incorporated in it. This controller provide the proportional with integral and derivative control or this controller combines proportional control with two additional adjustments, which help the unit automatically compensate for changes in the system. These adjustments, integral and derivative, are expressed in time-based units; they are also referred to by their reciprocals, RESET and RATE, respectively. The proportional, integral and derivative term must be individually adjusted or “tuned” to a particular system. It provide the most accurate and the stable control and is best suited for the system having relatively small mass, those which react very quickly to change in the energy added to the process. It is recommended to the system where the load changes often and the controller is expressed to compensate automatically due to frequent changes in set point, the amount of energy available, or the mass to be controlled. It is quite essential life support equipment for pre mature babies in hospitals. As most of the radiant warmers are imported from other countries because no Indian warmers provides accuracy more than ± 0. 25, so they are very costly. To provide additional features like weighting measurement, communication ports, living audio transmission at low cost is the aim of our paper.
3.1 The block diagram of body temperature and air temperature measurement and display and PID control of heater is as shown in Fig 1:
Figure 1: Block Diagram of Temperature Card
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